1
00:00:00,000 --> 00:00:04,000
Hi, R.J. I'm glad you found me. Dr. D. said you'd be coming by.

2
00:00:04,000 --> 00:00:08,000
Hi, Dr. Moisen. We're trying to figure out the final pieces to our mystery.

3
00:00:08,000 --> 00:00:11,000
Well, we had some tennis shoes washed up on the beach, and we don't know where they came from.

4
00:00:11,000 --> 00:00:13,000
That sounds like a real mystery.

5
00:00:13,000 --> 00:00:17,000
It really is. We think that the shoes came from someplace far away,

6
00:00:17,000 --> 00:00:19,000
and that the ocean currents brought them to Virginia.

7
00:00:19,000 --> 00:00:20,000
That's very possible.

8
00:00:20,000 --> 00:00:23,000
We know that the Gulf Stream flows along the coast of Virginia.

9
00:00:23,000 --> 00:00:26,000
We're not sure how the shoes got from the Gulf Stream onto the shore.

10
00:00:26,000 --> 00:00:29,000
Dr. D. suggests that we come learn more about coastal currents.

11
00:00:29,000 --> 00:00:30,000
Are coastal currents different?

12
00:00:30,000 --> 00:00:31,000
Yes, they are.

13
00:00:31,000 --> 00:00:35,000
Coastal currents can be located on the surface or on the bottom of the ocean,

14
00:00:35,000 --> 00:00:38,000
and they can be formed by density differences or tidal processes,

15
00:00:38,000 --> 00:00:40,000
but they're always found near the shoreline.

16
00:00:40,000 --> 00:00:42,000
Well, it doesn't sound like they're the answer.

17
00:00:42,000 --> 00:00:45,000
They could be, but first let's talk about dispersion.

18
00:00:45,000 --> 00:00:46,000
What's dispersion?

19
00:00:46,000 --> 00:00:49,000
Suppose you placed 100 yellow ducks in the center of a pool,

20
00:00:49,000 --> 00:00:51,000
turned off the pumps, and went away for 24 hours.

21
00:00:51,000 --> 00:00:54,000
Where do you suppose the ducks would be when you came back?

22
00:00:54,000 --> 00:00:57,000
Probably in the center of the pool, because there aren't any currents to move them around.

23
00:00:57,000 --> 00:01:01,000
Actually, you would find them randomly distributed or dispersed throughout the pool.

24
00:01:01,000 --> 00:01:03,000
Why wouldn't the ducks all be in the same place?

25
00:01:03,000 --> 00:01:07,000
Small-scale circulation patterns in the pool that move the water around

26
00:01:07,000 --> 00:01:10,000
will actually affect where these objects in the pool go.

27
00:01:10,000 --> 00:01:12,000
It could be something as small as a gust of air.

28
00:01:12,000 --> 00:01:17,000
But if the tennis shoes came from far away, they floated in currents that were already moving.

29
00:01:17,000 --> 00:01:20,000
Yes, but major currents have lots of eddies, filaments, swirls,

30
00:01:20,000 --> 00:01:23,000
and even jets that interact with and move objects.

31
00:01:23,000 --> 00:01:24,000
Where do eddies and filaments?

32
00:01:24,000 --> 00:01:28,000
Eddies are formed when a current doubles back to form a small whirl,

33
00:01:28,000 --> 00:01:31,000
and filaments are meanders that come off from the current.

34
00:01:31,000 --> 00:01:34,000
So maybe the eddies or filaments brought the tennis shoes into the shore.

35
00:01:34,000 --> 00:01:37,000
That's possible, because shoes caught in these small currents

36
00:01:37,000 --> 00:01:39,000
could travel across these major currents.

37
00:01:39,000 --> 00:01:41,000
Does the Gulf Stream have any eddies or filaments?

38
00:01:41,000 --> 00:01:42,000
Yes, lots of them.

39
00:01:42,000 --> 00:01:46,000
There are even large circulation eddies that break off from the Gulf Stream.

40
00:01:46,000 --> 00:01:48,000
I think that's the answer to our oil glob mystery,

41
00:01:48,000 --> 00:01:50,000
the loop current in the Gulf of Mexico.

42
00:01:50,000 --> 00:01:52,000
Now for the shoe mystery.

43
00:01:53,000 --> 00:01:56,000
Do coastal currents complete the process of bringing the shoes on shore?

44
00:01:56,000 --> 00:01:58,000
Yes, they can, but most of the shoes would not make it.

45
00:01:58,000 --> 00:02:01,000
If they float, won't they eventually end up on shore?

46
00:02:01,000 --> 00:02:03,000
No, most will end up in the Sargasso Sea.

47
00:02:03,000 --> 00:02:06,000
That's the place in the Atlantic Ocean with a lot of seaweed.

48
00:02:06,000 --> 00:02:07,000
Why there?

49
00:02:07,000 --> 00:02:13,000
Large circulation gyres in the North Atlantic Ocean move in circular clockwise pattern.

50
00:02:13,000 --> 00:02:17,000
Floating objects within these waters tend to move towards the center of rotation.

51
00:02:17,000 --> 00:02:20,000
I guess if the coastal currents could bring the shoes on shore,

52
00:02:20,000 --> 00:02:23,000
now all you have to do is find out where the container fell off the ship.

53
00:02:23,000 --> 00:02:24,000
Sounds like a good idea.

54
00:02:24,000 --> 00:02:26,000
And if the location's right,

55
00:02:26,000 --> 00:02:29,000
we will then know if it's possible that the currents, dispersions,

56
00:02:29,000 --> 00:02:31,000
and coastal currents brought them on shore.

57
00:02:31,000 --> 00:02:32,000
Thanks, Dr. Moisen.

58
00:02:32,000 --> 00:02:34,000
You're welcome. Glad I could help. Keep me posted.